The reductocondensation of 3-bromo-4-fluorobenzaldehyde (I) with morpholine (II) by means of NaBH(OAc)3 in dichloroethane gives 4-(3-bromo-4-fluorobenzyl)morpholine (III), which is condensed with N-methoxy-N-methylacetamide (IV) by means of BuLi in THF to yield 1-[2-fluoro-5-(4-morpholinylmethyl)phenyl]ethanone (V). The reaction of (V) with an excess diethyl carbonate (VI) by means of NaH affords the 3-oxopropanoate derivative (VII), which is treated with triethyl orthoformate (VIII) and Ac2O at 150 C to provide the ethoxymethylene compound (IX). The reaction of (IX) with morpholine-4-amine (X) in ethanol gives the aminomethylene derivative (XI), which is cyclized by means of NaH in hot THF to yield the quinolone-3-carboxylate (XII). Finally, this compound is condensed with 4-chlorobenzylamine (XIII) by heating at 190 C to afford the target quinolone-3-carboxamide.
The reductocondensation of 3-bromo-4-fluorobenzaldehyde (I) with morpholine (II) by means of NaBH(OAc)3 in dichloroethane gives 4-(3-bromo-4-fluorobenzyl)morpholine (III), which is condensed with N-methoxy-N-methylacetamide (IV) by means of BuLi in THF to yield 1-[2-fluoro-5-(4-morpholinylmethyl)phenyl]ethanone (V). The reaction of (V) with an excess diethyl carbonate (VI) by means of NaH affords the 3-oxopropanoate derivative (VII), which is treated with triethyl orthoformate (VIII) and Ac2O at 150 C to provide the ethoxymethylene compound (IX). The reaction of (IX) with piperazine-1-amine (X) in ethanol gives the aminomethylene derivative (XI), which is cyclized by means of NaH in hot THF to yield the quinolone-3-carboxylate (XII). Finally, this compound is condensed with 4-chlorobenzylamine (XIII) by heating at 190 C to afford the target quinolone-3-carboxamide.